A variety of different ladders are presently known to provide access between the ground and the engine service platform of a combine. Folding ladders incorporating spring biased over-centering linkages to hold the ladders in stowed or closed positions without the need of a separate latching mechanism, have been known since 1978 from U.S. Pat. No. 4,131,293 by Kindle. However, typical ladders for combines remain relatively short, on the order of three to five steps, and typically the ladders simply swing or pivot from deployed position into a position for storage. Additionally, several folding step arrangements are in the prior art. Also ladders that fold into or against a vehicle body are known, and there are known embodiments utilizing tracks to align a ladder into a storage hold.
However, there are certain recent model combines which have functional drawbacks inhibiting the deployment of ladders at the extreme rear end of the combine. Principally, among these drawbacks, is the difficulty of accommodating the discharge of straw and other M.O.G. (material other than grain) at the rear of the combine. That is, the ladder must be stored while also allowing ample room for the discharging straw and M.O.G. to flow freely, without being obstructed by the ladder. For purposes of homologation, the ladder, when deployed, must be long enough to extend beyond the discharge opening. Also, prior art ladders do not accommodate variations in vehicle height resulting from variation in the tire package. Furthermore, the ladders, when in the storage position at the rear, will accumulate straw and M.O.G. discharge, which subsequently spills onto the operator when he manually deploys the ladder into the service position. Also, the secondary mechanisms for positioning the access ladders in either the storage or working positions, such as push/pull cables or linkages would typically be inaccessible and unreliable at the rear of the combine.
An adjustable handle and latching mechanism, for positively positioning rear ladders, that would be reliable and accessible, would provide an unexpected advancement in combine harvester design, while satisfying a longfelt need for rearwardly accessing combine harvester engine service platforms, when there is a discharge port located at the rear of the combine.